The invention relates to a process for manufacturing sensors, especially temperature sensors, wherein respectively at least two spaced connection bridges arranged in the grid of a continuous carrier strip and having contact pads for electrically and mechanically firm connections are provided with respectively one sensor element, and wherein initially continuous edges of the carrier strip are subsequently separated from the connection bridges. The invention also relates to a temperature sensor, especially one made by the process of the invention.
From German utility model G 89 13 803.1, a resistance thermometer for measuring surface temperature is known, which has a metal layer temperature sensor in a housing. The metal layer temperature sensor is arranged in a plastic housing of electronic output elements with a cooling surface, wherein the connection formed for cooling the electronic component and provided with a bore hole forms the carrier of the metal layer temperature sensor. The connection surfaces of the metal layer temperature sensor are connected by contacting wires with the connections provided for the electronic output component, wherein the housing is bordered by the metal surfaces of the connection used as a carrier and the plastic casing enclosing the metal layer temperature sensor and the contact points of the bonding wires with the connections guided on the outside. The plastic casing consists of epoxide resin and is manufactured in an injection molding tool of an injection molding machine. An injection molding machine is known, for example, from DE-OS 23 58 911.
According to DE G 89 13 803.1, it is a matter of a resistance thermometer whose connection bridges can be manufactured by means of a continuous carrier strip (as it is usually used for micro-chip conductor frames and is known, for example, from EP 0 209 265 B1). Owing to the electrical connection by means of bonding wires, it is moreover a matter of a comparatively expensive finishing. Furthermore, it is not possible without more to use the resistance thermometer in any desired housing construction, as is usual owing to the increasing importance of temperature sensors, for example in motor vehicle engineering.
From DE 41 08 789 a temperature sensor is known which is suitable for the air stream of a turbo-charger in a motor vehicle; it uses an electronic component whose electrical resistance varies with temperature. The temperature responsive component sits in a flat indentation in an endface of the sensor housing. The component has no covering so that it can be completely exposed to the flow of the medium to be measured. The terminal wires of the component extend at a distance along the outside of the housing to contact tags. These wires are only insulated close to the component itself. The component is preferably a negative temperature coefficient pill. The connecting wires are of poor heat conductive material. The component can be protected by a bowed piece with two shanks which can be clipped on.
From DE 38 22 533 A1 the manufacturing of a temperature sensor using an automation method is known. A plastic material connecting element is first pressed onto two lamellar plugs joined by a bridge to mechanically join two sections of plug. The bridge is then separated so that the plugs are electrically isolated from each other. The ends of two connectors of a temperature sensor are soldered to sections of the plugs. A carrier housing for the plugs and the temperature sensor is then pressed on. The housing has a first section for protecting the temperature sensor and a second, beaker-shaped section in which the ends of the plugs are arranged for coupling to a suitable plug connector.
From DE 42 37 038 an injection-molded plastic temperature sensor, e.g., for an internal combustion engine, with a resistive temperature sensor is known. The temperature sensor has connector contacts soldered to the temperature sensing resistor and placed in an injection mold. A housing comprising a contact holder, connector flange and jacket is formed by injecting plastic material, carbon- or glass-fiber reinforced polyamide. A fixing flange may also be formed. The temperature sensor may be installed in a thermostat valve housing using an O-ring for sealing.
The invention sets for itself the objective of providing a manufacturing process for a temperature sensor with a measuring resistor as a sensor element. Here, besides an economical mass production according to the principle of a multi-unit preform, there also exists the possibility of adapting the sensor to locally provided housing shapes and nevertheless achieving a high stability.
The objective is accomplished according to the invention in that respectively at least two connection bridges in continuous carrier strips provided for connection with a sensor element are at least partially so injection molded around with plastic, that respectively at least two plastic bodies arise arranged spaced from each other on the connection bridges, wherein between plastic bodies of adjacent connection bridges, spacer elements made of plastic are at least partially formed in the same injection process, while contact pads and ends of the connection bridges remain free of plastic.
In one advantageous embodiment of the process, respectively two adjacent plastic bodies are connected by spacer elements, wherein the respective plastic body/spacer element boundary is constructed as a rupture joint. Advantageously, the outer edges of the carrier strip are, in connection with the injection process in the injection molding tool, separated by punching from the connection bridges, wherein it is practically a matter of an operation connected with the injection process.
The sensor elements are then placed with their respective connection regions on the contact surfaces of the connection bridges and soldered for electrical and mechanical connection, wherein a subsequent electrical function test can be conducted in the continuous preform or multi-unit preform. For separation of sensors from the multi-unit preform, the spacer elements are broken in the region of their respective rupture joints. At least two plastic bodies are provided per sensor element, whereby respective interstices are created along the connection bridges between the plastic bodies or between sensor element and adjacent plastic body by bending along the connection bridges into a suitable form for their subsequent use as sensors. Advantageously, adjacent regions of the plastic body are pre-shaped on respectively one connection bridge, such that they serve as a stop upon bending.
It proves to be advantageous that, according to the process, a two-dimensional sensor arrangement is producible, which then for technical use can be adapted to the spatial structural conditions of the environment or the housing. Here, it proves to be especially advantageous that several plastic injection molding elements can be applied on the carrier arrangement, which then guarantee bending zones for the spatial adaptation for accommodating the sensor in special housings or local environments.
The objective is accomplished for a sensor, in which a sensor element is connected electrically and mechanically firmly via its own connection contacts with contact pads of a carrier arrangement, in that the carrier arrangement has at least two longitudinally extending connection bridges arranged at a distance from each other, which are connected mechanically fast by at least one injection molding element as a plastic body partially encasing them, wherein at one end of the carrier arrangement the connection bridges have contact pads for electrical and mechanical connection with the sensor element, while the other, opposite-lying end of the carrier arrangement is provided for connection with a measuring facility.
In one advantageous embodiment at least two plastic bodies are provided arranged at a distance from each other, wherein viewed along the respective axis of the connection bridges, interstices on the connection bridges situated between sensor element and plastic body or between the plastic bodies are constructed as bending zones for adaptation to predetermined housing structures.
Preferably, adjacent areas of plastic bodies are formed respectively in pairs as a stop for a bending operation along the axis of the connection bridges.
It proves to be especially advantageous that bonding wires or special supply leads can be dispensed with, wherein the sensor is also insertable into complex shaped housings. Here, an automatable processing is also advantageously possible.